Feature

John Gille: Searching for Patterns in the Clouds
07.08.04
Photograph of John Gille
Picture clouds floating high in the sky. As the air warms during the day, the clouds grow higher and higher. It seems the clouds can do just about anything they want to -- form any shape, reach any height.

Image to right: John Gille turned a life-long fascination with physics, chemistry and math into a career with NASA. Credit: NASA

Most clouds, however, eventually encounter a ceiling, a subtle layer of atmosphere only four kilometers thick. This thin layer, scientifically named the "tropopause transition layer," caps the much thicker layer of denser atmosphere in which we live. It lies just below a vast, almost cloudless layer called the stratosphere.

This tropopause ceiling, most evident in the tropics, puts the lid on clouds while allowing water vapor and ozone to be exchanged. How this works is the mystery captivating the research interests of John Gille, a physicist at the University of Colorado in Boulder and the National Center for Atmospheric Research.

Gille looks forward to gathering important atmospheric data with an instrument that his team of scientists has developed -- a remote sensor that will ride aboard NASA's Aura satellite. The planned orbital destination, at an altitude of 705 kilometers (438 miles), should position this sensor, the High Resolution Dynamic Limb Sounder (HIRDLS, pronounced "hurdles"), in the perfect spot for probing the mysterious tropopause transition layer.

What Will HIRDLS Measure?

All molecules emit radiation. HIRDLS specifically measures the infrared radiation emitted by molecules. Although we cannot see infrared light with our eyes, it is just as real as visible light, but with longer wavelengths and lower frequencies.

Different molecules emit different frequencies of infrared light as they absorb and emit energy. By studying known samples with laboratory instruments, scientists already know what frequencies a vast variety of molecules emit. So if HIRDLS measures at these frequencies, they will know what molecules, and how many, are present in a particular part of the atmosphere.

Gille's talented team includes engineers who design, build and test the hardware; software engineers, who develop the programs and code for crunching the data; and scientists, who make sure the instrument is set to measure the important and interesting chemistry of the atmosphere.

It's Gille's job to keep everyone on the same page. He believes that success hinges on everyone carrying out their own responsibilities while having some understanding of what's going on in other parts of the program.

A Scientist is Born

Gille's fascination with physics started in elementary school. He's not certain what sparked his interest, but it might have been the challenge of understanding a hard subject.

News coverage about nuclear physics fascinated him. Chemistry, physics and math were his high school favorites. Attending high school, he recalls having excellent chemistry and physics teachers. His math classes were also good, but Gille says, "They didn't get as far as they do now." So he taught himself some calculus, "just by reading myself."

Managing to get in some skiing and hiking for fun, he describes a career in science as marvelous and fascinating. He loves working on problems where science and engineering intersect. "I really enjoy taking a set of scientific questions and then calling on available technology to design something that will find the answers."

Adapted with permission: ChemMatters magazine © American Chemical Society 2002
Edited by Dan Stillman, Institute for Global Environmental Strategies